Color stripping process



Patented Nov. 24, 1936 UNITED STATES PATENT OFFICE COLOR STRIPPING PROCESS No Drawing. Application June 4, 1935, Serial No. 24,984. In Great Britain June 12,1934

18 Claims.

This invention relates to a process of stripping dyes from dyed textile material, and more particularly to the use of quaternary phosphonium salts and ternary sulphonium salts as reagents for promoting stripping processes.

In the copending application of Evans and Lawrie, Serial No. 661,180, filed March 16, 1933, which became U. S. Patent No. 2,003,928 onJune 4, 1935, and in British Patent Number 400,239, a process is described for stripping textile materials which have been dyed with azoic colors which comprises treating said textile materials with a reducing liquor containing an amine or an amine salt, one radical in which comprises a straight or branched carbon chain of not less than ten carbon atoms. Among the stripping assistants mentioned in this patent and application are: beta diethylamino ethyl oleyl amide or its acetate or hydrochloride, heptadecyl amine or its hydrochloride, octadecyl pyridinium bromide, cetyl pyridinium bromide, cetyl pyridinium chloride, octadecyl trimethyl ammonium iodide, cetyl trimethyl ammonium bromide,,cetyl triethyl ammonium bromide, cetyl trimethyl ammonium iodide, and beta hydroxyethyl-N-octadecyl morpholinium bromide.

In the copending application of Evans and Lawrie, Serial No. 718,741, filed April 2, 1934, which became U. S. Patent No. 2,019,124 on October 29, 1935, a similar process is described for stripping textile materials which havebeen dyed with alizarine, basic or vat dyestufis by treating them in a liquor containing one of the amines or amine salts, mentioned in the preceding paragraph, and also where necessary, an acid, alkali, reducing agent, soluble soap, carboxylic acid, and a sulphonic acid or sulphuric ester as defined in this copending application.

This invention has for an object the provision of an improved or modified technically advantageous, economical process of stripping textile materials, particularly adapted to the entire or substantially entire removal of solid shades obtained by azoic, alizarine, basic or vat dyestuffs. A further object of the invention is to utilize recently discovered sulphonium and phosphonium compounds in processes in which they display considerable technical value. Other objects will appear hereinafter.

These objects are accomplished according to the present invention by treating textile materials which have been dyed with the said dyestuffs in a liquor containing a quaternary phosphonium salt or a sulphonium salt, one radical in which comprises a straight or branched chainoi not less Example 1 20 parts of cotton dyed with -chloro-o-toluene-azo-2:3-hydroxynaphthoic anilide are boiled for half an hour in a solution of 3 parts of sodium hydrosulphite conc. powder, 1.8 parts of sodium hydroxide and 0.6 part of dimethyl cetyl sulphonium methyl sulphate in 1000 parts of water. The dyeing is thus stripped to a pale yellow. It

is then immersed cold in tw. sodium hypochlorite solution for hour if a clear white is required.

Example 2 parts of cotton which had been given two dips in a vat containing 5 parts per 1000 parts of water of Indigo LL 60% Colour Index No. 1177) are boiled for hour in a solution of-- Parts Sodium hydrosulphite conc. powder 3.3 Sodium hydroxide s 2.0 Dimethylcetyl sulphonium methyl sulphate 1.3 Sodium stearate 0.9

Water in 1000.0

The material is rinsed lightly in cold water and treated for 10 minutes in a tw. solution of *"sodium hypochlorite to obtain a clear white.

Ecample 3 30 parts of cotton dyed with a 20% shade of Caledon jade greemXS (Color Index No. 1101) are treated at 95100 C. for half an hour in a solution containing 2.0 parts sodium hydroxide, 3.3 parts sodium hydrosulphite concentrated powder, 0.4 parts hexadecyl triethyl phosphonium bromide, 0.26 part soap in 1,000 parts of water. The material is then rinsed lightly in cold water and treated for 10 minutes in k" tw. solution of sodium hypochlorite, rinsed well, and soured in tw. solution of hydrochloric acid, rinsed well, and then soaped at the boil for 20 minutes in a solution containing 2 parts soap in 1,000 parts of water. The material is stripped to a very pale green shade.

Example 4 30 parts of cotton yarn dyed with Acronol yellow TS (Color Index No. 815) on a tannin mordant are treated for one hour at the boil in a solution containing 1.6 parts of hexadecyl triethyl phosphonium bromide in 1,000 parts of water. The material is then rinsed well with water and treated for 20 minutes at the boil in a solution containing 2 parts of soap in 1,000 parts of water. The material so treated is completely stripped to white.

Example 5 30 parts of cotton dyed with Auramine OS (Color Index No. 655) on a tannin mordant are treated for one hour at the boil in a solution containing 1.6 parts of dimethyl hexadecyl sulphonium methyl sulphate in 1,000 parts of water. The material is subsequently treated as in Example 4 and a complete strip to a white is obtained.

Example 6 30 partsof cotton dyed with alizarine on an aluminium mordant are treated at the boil for three hours in a solution containing 8.0 parts sodium hydroxide, 14.0 parts sodium hydrosulphite concentrated powder and 1.66 parts hexadecyl triethyl phosphonium bromide in 1,000 parts of water. The material is then rinsed and treated for 15 minutes in tw. solution of sodium hypochlorite, rinsed well, soured, and then soaped at the boil for 20 minutes in a solution containing 2 parts of soap in 1,000 parts of water. The material is stripped to a white.

Example 7 Cotton yarn (30 parts) dyed with an 8% shade of Durindone red 3BS (Colour Index No. 1212) is treated at the boil for hour in a solution containing- The material is then treated as in Example 3. The material is stripped to a very pale shade.

Example 8 Natural silk (30 parts) dyed with the 4-bromoo-anisidide of 2:3-hydroxynaphthoic acid, coupled with diazotized 4-nitro-o-anisidine, is treated for 30 minutes'at the boil in a solution containing 1.3 parts of acetic acid (30%), 2.6 parts formosol (sodium sulphoxylate formaldehyde), 0.6 part hexadecyl triethyl phosphonium bromide and 0.6 part anthraquinone in 1,000 parts of water. The material is then rinsed well, treated for one hour at 85 C. in a 1 volume solution of hydrogen peroxide, and then soaped at the boil for 30 minutes in a solution containing 2 grammes of soap, in 1,000 parts of water. The material is completely. stripped by this treatment.

The preferred phosphonium compound for use in the present invention is hexadecyl triethyl phosphonium bromide. The preferred sulphonium compound for use in the present invention is dimethyl hexadecyl sulphonium methyl sulphate.

The method of preparing dimethyl cetyl sulphonium -methyl sulphate, hexadecyl triethyl phosphonium bromide, and other phosphonium and sulphonium compounds, which may be used in their place, will now be described.

1. Hexadecyl (cetyl) triethyl phosphonium bromide may be made by interacting triethyl phosphine and cetyl bromide.

2. Cetyl trimethyl phosphonium bromide may be made by interacting trimethyl phosphine and cetyl bromide.

3. Dodecyl trimethyl phosphonium bromide may be made by interacting dcdecyl bromide and trimethyl phosphine.

4. Dodecyl triethyl phosphonium bromide may be prepared by reacting triethyl phosphine with dcdecyl bromide in ethereal solution at 80 C. for 14 hours.

5. octadecyl trimethyl phosphonium bromide may be made by interacting octadecyl bromide with trimethyl phosphine.

6. Octadecyl, triethyl phosphonium bromide may be made by interacting triethyl phosphine and octadecyl bromide.

7. Tetradecyl .trimethyl phosphonium bromide may be made by interacting trimethyl phosphine and tetradecyl bromide.

8. Tetradecyl triethyl phosphonium bromide may be made by interacting triethyl phosphine and tetradecyl bromide.

9. Decyl trimethyl phosphonium bromide may be made by interacting trimethyl phosphine and decyl bromide.

10. Decyl triethyl phosphonium bromide may be made by interacting decyl bromide with triethyl phosphine.

11. Cetyl dimethyl sulphonium methyl sulphate is made by heating cetyl methyl sulphide with dimethyl sulphate. The cetyl methyl sulphide is itself .made by interacting equivalent quantities of cetyl mercaptan and dimethyl sulphate in alkaline solution.

12. Benzyl cetyl methyl sulphonium methyl sulphate is made as follows:-

1,000 parts of cetyl mercaptan are treated with parts of sodium in methanol and then heated for 1 hour at about 80 C. with 4'70 parts of benzyl chloride. The product is poured into water, extracted with ether, the ethereal layer distilled and the fraction b. p. 250-260/40 mm. collected. parts of this cetyl benzyl sulphide are heated with 37 parts of dimethyl sulphate at about 80 C. for about hour and then cooled when the benzyl cetyl methyl sulphonium methyl sulphate crystallizes. I

13. Dodecyl dimethyl sulphonium bromide may be made by heating dcdecyl methyl sulphide with methyl bromide until a completely water-soluble product is obtained. Dodecyl methyl sulphide is itself made by interacting equivalent quantities of dodecyl mercaptan and dimethyl sulphate in aqueous alkaline medium.

14. Benzyl methyl dcdecyl sulphonium chloride may be made by heating dcdecyl methyl sulphide with benzyl chloride until a completely .water-soluble compound is produced.

15. Benzyl ethyl decyl sulphonium chloride may be made by interacting benzyl chloride with decyl ethyl sulphide.

16. Benzyl methyl dcdecyl sulphonium methyl sulphate may be obtained by treating the mercaptan derived from dodecyl bromide with a mixture of sodium ethoxide and benzyl chloride and finally treating the resulting product with dimethyl sulphate.

17. Benzyl ethyl dodecyl sulphonium chloride may be made by interaction of benzyl chloride with dodecyl ethyl sulphide.

18. Dimethyl dodecyl sulphonium methyl sulphate may be made by heating a mixture of 264 parts of methyl dodecyl sulphide and 165 parts of dimethyl sulphate at 90-100 C. until watersoluble.

19. Decyl dimethyl sulphonium hydroxide may be prepared as described in Liebigs Annalen der Chemie, vol. 472, page 139.

20. Decyl dimethyl sulphonium iodide may be prepared as described in the reference just previously mentioned.

21. Methyl butyl octadecyl sulphonium chloride may be made from methyl octadecyl sulphide and butyl chloride.

22. Methyl butyl hexadecyl sulphonium chloride may be made from methyl hexade'cyl sulphide and butyl chloride.

23. Methyl butyl'tetradecyl sulphonium chloride may be made by interacting methyl tetradecyl sulphide with butyl chloride.

24. Methyl butyl dodecyl sulphonium chloride may be made by reacting butyl chloride with methyl dodecyl sulphide.

25. Methyl butyl decyl sulphonium chloride may be made by reacting methyl decyl sulphide with butyl chloride.

26. Methyl butyl octadecyl sulphonium methyl sulphate may be made frombutyl octadecyl sulphide and dimethyl sulphate.

2'1. Methyl butyl hexadecyl sulphonium methyl sulphate may be made from butyl hexadecyl sulphide and dimethyl sulphate.

28. Methyl butyl tetradecyl sulphonium methyl sulphate may be made by reacting butyl tetradecyl sulphide with dimethyl sulphate.

29. Methyl butyl dodecyl sulphonium methyl sulphate may be made by interaction of butyl dodecyl sulphide with dimethyl sulphate.

30. Methyl butyl decyl sulphonium methyl sulphate may be made by reacting butyl decyl. sulphide with dimethyl sulphate.

31. Methyl benzyl hexadecyl sulphonium chloride may be made by treating methyl hexadecyl sulphide with benzyl chloride.

32. Methyl cyclohexyl hexadecyl sulphonium chloride may be made by reacting cyclohexyl chloride with methyl hexadecyl sulphide.

It is also contemplated that mixtures of any of the above mentioned assistants may be employed. The use of mixtures is frequently to be preferred for reasons of economy, since it is usually cheaper to prepare these compounds from a mixture of the alkyl halides which are made from coconut oil alcohols than it is to use a single alkyl halide as an intermediate from which to prepare these compounds. It is also contemplated that these phosphonium and sulphonium compounds may be used in combination with the amine salts mentioned in the second paragraph of this specification.

When stripping textile materials dyed with basic dyestuffs, it is usually suflicient to heat in an aqueous liquor containing the salt. When stripping azoic, alizarine and vat dyestuifs, a

reducing agent and an acid or alkali is usually J necessary,.and further with vat dyestuffs a soluble soap, a carboxylic acid or a sulphonic acid or sulphuric ester is also desirable. When strip-. ping wool, silk and other animal fiber, alkali is chlorite.

preferably avoided as it is liable to cause injury.

Where reducing agents are used, these quaternary salts besides assisting in the removal of color also strip more levelly. More level stripping is an advantage where the material only 5 needs partial stripping, for example, where the material which has been dyed an incorrect shade is to be partially stripped and then redyed.

In case the stripping operation leaves the fiber slightly tinged with the dyestuff, a supplemenr. tary chlorine or chemick treatment for vegetable fiber may be applied to further improve the ground. A convenient reagent to use for this purpose is a dilute solution of sodium hypo- In the case of animal fibers, a supl5 plementary treatment withhydrogen peroxide is sometimes beneficial.

In place of soap in the foregoing examples, other detergents may be used. By soaps we mean salts of carboxylic acids containing an aliphatic saturated or unsaturated radical containing a carbon chain of not less than ten carbon atoms. As examples of other detergents, compounds of the class represented by the general formulae RSOsH and ROSOsH and soluble salts thereof where R. is an aliphatic saturated or unsaturated radical containing a carbon chain of not less than ten carbon atoms, are to be mentioned. Examples of compounds falling within this class of detergents are; the sulphated long chain alcohols such as those disclosed in Bertsch Patents 1,968,793-7; oleyl taurine and its derivatives (see U. S. Patent 1,932,180); and acid sulphates made from higher ethers of polyhydroxy alcohols such as the sulphation products of batyl alcohol, selachyl alcohol, and chimyl alcohol disclosed in the British Patent 398,818.

Advantages of our invention are that it provides a ready means of stripping dyestuffs which are normally diflicult to strip.

When we speak of dyed textile materials, we

include printed textile material, but we do not include discharging; that is to say, the local removal of color for the purpose of making color patterns. By vat colors we mean anthraquinone and indigoid vat colors and vat colors of the hydron blue type. 1

As many apparently widely different embodiments of this invention may be made without widely departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

We claim:

1. A process of stripping dyes from dyed textile materials which comprises treating the dyed materials with an aqueous solution of a salt selected from the group consisting of quaternary phosphonium and sulphonium salts, one radical in which comprises an aliphatic chain of not less than ten carbon atoms.

2. A process according to claim 1 in which the aqueous solution also contains a reducing agent.

3. A process according to claim 1 in which the stripping treatment is followed by a bleaching treatment.

4. A process of stripping dyes from dyed textile materials which comprises treating the dyed materials with an aqueous solution of a quaternary phosphonium salt which includes three alkyl radicals containing one or two carbon atoms and one alkyl radical which contains from ten to eighteen carbon atoms.

5. A process according to claim 4 in which the aqueous solution also contains a reducing agent.

6. A process according to claim 4 in which the stripping treatment is followed by a bleaching treatment.

7. A process of stripping dyes from dyed textile materials which comprisestreating the dyed materials with an aqueous solution of hexadecyl triethyl phosphonium bromide.

8. A process according to claim '7 in which .the aqueous solution also contains sodium hydrosulphite.

9. A process according to claim 7 in which the stripping treatment is followed by a bleaching treatment with a solution of sodium hypochlorite.

10. A process according to claim '7 in which the stripping treatment is followed by a bleaching treatment with a solution of hydrogen peroxide.

11. A process of stripping dyes from dyed textile materials which comprises treating the dyed materials with an aqueous solution containing sodium hydrosulphite, sodium hydroxide, and

hexadecyl triethyl phosphonium bromide;.rinsing, treating with a solution of sodium hypochlorite, and soaping.

12. A process of stripping dyes from dyed textile materials which comprises treating the'dyed materials with an aqueous solution containing tile materials which comprises treating the dyed materials with an aqueous solution containing dimethyl cetyl sulphonium methyl sulphate.

16. A process according to claim 15 in which the aqueous solution also contains sodium hydrosulphite.

17. A process according ,to claim 15 in which the stripping treatment is followed by a bleaching treatment with a solution of sodium hypochlorite.

18. A process oi? stripping dyes from dyed textile materials'which comprises treating the dyed materials with an aqueous solution containing sodium hydroxide, sodium hyd'rosulphite, and dimethyl cetyl sulphonium methyl sulphate; and subsequently treating said materials in a dilute solution of sodium hypochlorite.

JOHN GWYNANT EVANS.

HENRY ALFRED PIGGO'II. 

